The present invention relates to an image reading unit and an image reading apparatus provided with the same, in which a light reflected from an original document through a plurality of reflecting devices is condensed or focused and reduced by a condensing device, to thereby read an image on the document by a reading device.
In a general image reading unit or image reading apparatus using the same, which reads an image on a document by reducing a size thereof, it is necessary to secure a predetermined optical path length in order to read the image of the document. The optical path is required to have a certain length from a document reading position to an image sensor, depending on a width of the document, a lens as a condensing device, and the image sensor such as a charge coupled device (CCD) as a reading device. Therefore, in a conventional apparatus, in order to make the apparatus small while the predetermined optical length is secured, a plurality of reflecting devices such as mirrors is used for reflecting the light from the document several times.
As the conventional image reading apparatus or the conventional image reading unit described above, there have been known an image reading unit and image reading apparatus disclosed in Japanese Patent Publication (KOKAI) No. 63-59259 and Japanese Patent Publication (KOKAI) No. 09-69915. Each of these image reading units includes a light source for irradiating light to an image surface of the document; a plurality of reflecting mirrors for reflecting the light irradiated from the light source and reflected from the document; a condenser lens for receiving the light reflected from the document through the reflecting mirrors to thereby condense the light; and an image sensor for converting the reflected light passing through the condenser lens into an electric signal to read the image.
In the image reading unit disclosed in Japanese Patent Publication (KOKAI) No. 63-59259, a pair of reflecting mirrors is provided above the condenser lens, and while the predetermined optical path length is secured by reflecting the light reflected from the document several times between the reflecting mirrors of the pair, it has been tried to reduce the size of the image reading unit. Also, in the image reading unit disclosed in Japanese Patent Publication (KOKAI) No. 09-69915, a plurality of mirrors is disposed below the lens, and by changing the optical path direction below the lens, it has been tried to make the image reading unit small while the predetermined optical path length is secured.
In the conventional units described above, however, it is necessary to have a space for providing the mirrors disposed above or below the lens and the optical paths reflected by the respective mirrors. Therefore, according to the conventional structures, it is difficult to further reduce the size of the image reading unit, especially, to make a thinner unit.
The present invention has been made in view of the above problems in the prior arts, and an object of the invention is to provide an image reading unit and an image reading apparatus provided with the same, in which a reciprocating optical path is formed between a condenser lens and an image sensor to make the reading unit small.
Further objects and advantages of the invention will be apparent from the following description of the invention.